Monjack directed, produced, and wrote the B-movieTwo Days, Nine Lives in 2000.[9] He received story credit for the 2006 biographical film Factory Girl about Warhol actress/model Edie Sedgwick.[10] Director George Hickenlooper contended that "Monjack had nothing to do with Factory Girl" and that "he filed a frivolous lawsuit against us [...] making bogus claims that we had stolen his script. He held us literally hostage and we were forced to settle with him as he held our production over a barrel." Monjack denied these claims.[11] In 2007, E! News reported that Monjack was slated to direct a film adaptation of D. M. Thomas's novel about Sigmund Freud, The White Hotel, with Brittany Murphy cast in a leading role.[12]

Monjack married Simone Bienne in Las Vegas in November 2001;[13][14] they separated five months later,[14] and were divorced in 2006.[13] That year,[4] he met actress Brittany Murphy (although he claimed to have met her when she was a teenager and stayed in touch[15]). In April[16] 2007, they married in a private Jewish ceremony at their Los Angeles home.[1] The couple did not announce their engagement beforehand and rarely made public appearances together before their marriage.[12] On 20 December 2009, Murphy died after collapsing in their bathroom.[2] The cause was later revealed to be pneumonia, with secondary factors of iron-deficiency anemia and multiple prescription drug intoxication. [17]

In January 2010, Monjack's mother, Linda Monjack, told People that her son was "unwell, and the doctors are carrying out tests. On whether he has a heart problem, it is not really for me to say, you must ask him, but yes, there have been health problems in the past. I believe it's common knowledge, and it's been in the press that he had a slight heart attack a week before Brittany's death."[18]

Monjack was found dead on 23 May 2010 in his house in Hollywood, according to the Los Angeles County coroner's office. Law enforcement sources say the Los Angeles Fire Department was called there for a medical emergency after Murphy's mother, Sharon, found Monjack unconscious in the master bedroom around 9:20 pm, and then called 911. Paramedics arrived; Monjack was pronounced dead at 9:45 pm after suffering a fatal myocardial infarction.[19]

The coroner's report found the cause of Monjack's death to be acute pneumonia and severe anemia, similar to the causes attributed to his wife's death five months earlier in the same house.[20] He was buried next to Murphy at Forest Lawn cemetery in the Hollywood Hills.[14][21]